1. Field of the Invention
The present invention relates to an observation system which estimates a surface shape of a specimen based on perspective information calculated from each captured image provided by emitting lights to the same observing position on a specimen more than once, and displays it as a stereoscopic image.
2. Description of the Related Art
Generally, when displaying a stereoscopic image (a three-dimensional image) on a monitor, two imaging systems having a difference in viewpoint (a binocular parallax) are used, and respective captured images are combined and displayed. In an observation apparatus applied to an endoscope or the like having an image sensor mounted therein, at the time of conducting an endoscopic operation using an arm having a treatment tool disposed thereto, three-dimensional display to stereoscopically display an irregular state of a surface of a specimen as a treatment target in an easy-to-understand manner is desired.
It is known than perspective information required to display the irregular state of the specimen surface is acquired by using a so-called triangulation system of, for example, applying light to a measurement position, taking the reflected light into an image sensor, and calculating the perspective information as a distance from an image forming position on a light receiving surface to an observing position, and that the irregular state of the observing position can be calculated from this perspective information.
However, in the observation system in an endoscope or the like, a decrease in diameter of an inserting section is desired, a forceps hole and others are formed in a distal end surface of this section, an arrangement space where imaging optical systems (compound eyes) are arranged is not provided, and hence configuring a three-dimensional image by one imaging optical system is desired. For example, Patent Literature 1: Jpn. Pat. Appln. KOKOKU Hei 6-76888 proposes a measurement method of moving one light source to one imaging optical system so that diffusion lights having the same luminous intensity are applied to an immovable observing position from different positions respectively, measuring a luminance distribution of acquired captured images, calculating a distance distribution of surfaces of measurement positions, and measuring an irregular state of the observing position. Here, a distance from the light source to the observing position surface is calculated based on the fact that the luminance is in inverse proportion to a square of a distance from the light source to each measurement position, and the distance distribution is calculated from the luminance distribution provided by reflected lights.
The observation system according to the present invention acquires perspective information which suggests an irregular state of a specimen surface from captured images captured under illumination lights sequentially applied at continuous timings through irradiation windows at different positions aligned in one imaging optical system, and displays a three-dimensional observation image based on the perspective information.
Furthermore, the observation system images a specimen under illumination lights applied at different timings through irradiation windows arranged near one image sensor, generates optical information included in each image, calculates values of light volumes included in the optical information output from identical-point originated pixels, which have imaged an identical point as the same characteristic point on the specimen, in the respective pixels as a relative distance from an image sensor, compares the optical information between the pixels, and determines the identical point on the specimen as a flat surface portion or an inclined portion on the basis of a comparison result, associates the distance with the flat surface portion or the inclined portion, estimates a surface shape of the specimen, and displays a three-dimensional image of the specimen.